There have been numerous types of clamps for use in terminating ropes and cable and other types of flexible and rigid conductors under tension. Certain of these clamps use a wedging action whereby the greater the tension on the rope, the tighter the clamp will grip the rope. Many of these wedge type clamps use a tapered plug which is slidably mounted within a complementary tapered bore found in an outer sleeve. Some examples of these prior tapered plug-sleeve type clamps are shown in U.S. Pat. Nos. 222,125; 508,587; 831,548; 2,078,051; 3,852,850; 3,879,147 and 3,952,377.
Although many of these prior clamp constructions do perform satisfactory for certain types of rope and cable terminations, they have not been satisfactory for use in providing a terminal clamp for certain recently developed nonmetallic synthetic rope. This rope is formed of a continuous filament, impregnated fiberous material which provides an extremely flexible, strong member, having a very high strength to weight ratio. This type of rope is nonconductive and is noncorroding.
It also has an extremely high modulus of elasticity and strength in the axial direction. Due to its corrosive resistance and nonconductivity, it is extremely useful on ships or for other marine installations since it is unaffected by the salt water which readily attacks metal cables and ropes. It also has many uses in the electrical industry for construction and maintenance applications. Its noncorrosiveness also provides an extremely long life without loss of strength and holding power.
One disadvantage of such synthetic fiberous rope is that it is relatively brittle when bent or experiencing a compressive load transverse to the axis of the rope. This characteristic makes it extremely difficult to provide a satisfactory terminal connector or clamp since most clamps exert a strong compressive force on the rope over a very small area which will cause the individual fibers to crimp or bend which will break or seriously affect the safety factor of the rope.
One known method of terminating such fiberous rope is a "potting" procedure in which the rope end is placed in a void of a clamp and filled with a chemical composition which hardens about the rope to secure it in the clamp. Another type of rope has a terminal loop woven into the end of the rope at the factory. Either type of terminal is relatively expensive and unsatisfactory for use in the field and is suitable only when the exact length is known and remains constant when installed.
Thus, the need has existed for a clamp construction which will provide a small compressive force over a relatively long length of rope to prevent damage to the fragile synthetic fibers in the transverse direction, yet will maintain sufficient gripping force on the rope even when the rope tension varies and is subjected to a highly corrosive environment.